Depression of Type I Diacylglycerol Kinases in Pancreatic β-Cells From Male Mice Results in Impaired Insulin Secretion
Depression of Type I Diacylglycerol Kinases in Pancreatic β-Cells From Male Mice Results in Impaired Insulin Secretion
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DOI：
10.1210/en.2013-1356
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发表时间：
2013-11-01
期刊：
影响因子：
4.8
通讯作者：
Ishikawa, Tomohisa
中科院分区：
文献类型：
--
作者：
Kaneko, Yukiko Kurohane;Kobayashi, Yosuke;Ishikawa, Tomohisa
甘油二酯激酶（DGK）催化甘油二酯（DAG）转化为磷脂酸。本研究探讨了DGK在胰腺β细胞中的表达和功能。在小鼠胰岛和β细胞系MIN 6中检测I型DGK同种型（α、β、γ）的mRNA表达。还在小鼠β细胞和MIN 6细胞中检测到DGK α和DGK γ的蛋白表达。I型DGK抑制剂R59949抑制高K+和葡萄糖诱导的MIN 6细胞胰岛素分泌。此外，单敲低DGK α或DGK γ的小干扰RNA轻微，但显着降低葡萄糖和高K+诱导的胰岛素分泌，和双敲低进一步降低它们的水平与R59949诱导的水平相当。R59949和DiC 8（一种膜渗透性DAG类似物）降低了MIN 6细胞中葡萄糖和高K+引起的细胞内Ca 2+浓度升高。在表达绿色荧光蛋白标记的DGK α或DGK γ的MIN 6细胞中的实时成像显示，DGK激活剂佛波醇12-肉豆蔻酸酯13-乙酸酯迅速诱导DGK γ易位至质膜，而高K+缓慢地将DGK α和DGK γ易位至质膜。R59949可增加高KCl刺激的MIN 6细胞DAG含量，而不增加高糖刺激的细胞DAG含量，但降低磷脂酸含量。最后，证实R59949抑制高K+诱导的小鼠胰岛胰岛素分泌和葡萄糖诱导的大鼠胰岛胰岛素分泌。这些结果表明，DGK α和DGK γ存在于β细胞中，并且这些DGK的抑制导致细胞内Ca 2+浓度降低，从而减少胰岛素分泌。
Diacylglycerol kinase (DGK) catalyzes the conversion of diacylglycerol (DAG) to phosphatidic acid. This study investigated the expression and function of DGK in pancreatic beta-cells. mRNA expression of type I DGK isoforms (alpha, beta, gamma) was detected in mouse pancreatic islets and the beta-cell line MIN6. Protein expression of DGK alpha and DGK gamma was also detected in mouse beta-cells and MIN6 cells. The type I DGK inhibitor R59949 inhibited high K+- and glucose-induced insulin secretion in MIN6 cells. Moreover, single knockdown of DGK alpha or DGK gamma by small interfering RNA slightly but significantly decreased glucose- and high K+-induced insulin secretions, and the double knockdown further decreased them to the levels comparable with those induced by R59949. R59949 and DiC8, a membrane permeable DAG analog, decreased intracellular Ca2+ concentration elevated by glucose and high K+ in MIN6 cells. Real-time imaging in MIN6 cells expressing green fluorescent protein-tagged DGK alpha or DGK gamma showed that the DGK activator phorbol 12-myristate 13-acetate rapidly induced translocation of DGK gamma to the plasma membrane, whereas high K+ slowly translocated DGK alpha and DGK gamma to the plasma membrane. R59949 increased the DAG content in MIN6 cells when stimulated with high KCl, whereas it did not increase the DAG content but decreased the phosphatidic acid content when stimulated with high glucose. Finally, R59949 was confirmed to inhibit high K+-induced insulin secretion from mouse islets and glucose-induced insulin secretion from rat islets. These results suggest that DGK alpha and DGK gamma are present in beta-cells and that the depression of these DGKs causes a decrease in intracellular Ca2+ concentration, thereby reducing insulin secretion.